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Updated: Jun 21, 2025
07:58
Data Processing Methods for 3D Seismic Imaging of Subsurface Volcanoes: Applications to the Tarim Flood Basalt
Published on: August 7, 2017
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Constraining Earth's nonlinear mantle viscosity using plate-boundary resolving global inversions
Jiashun Hu1, Johann Rudi2, Michael Gurnis3
1Department of Earth and Space Sciences, Southern University of Science and Technology, Shenzhen 518055, China.
Summary
This study reveals key mantle viscosity parameters controlling plate tectonics. A new method accurately models global plate motions, providing insights into subduction zone strength and earthquake dynamics.
Area of Science:
- Geophysics
- Tectonophysics
- Computational Geodynamics
Background:
- Mantle viscosity variations critically influence mantle convection and plate tectonics.
- Previous inverse methods struggled with complex viscosity gradients and nonlinearities in Earth's mantle.
Purpose of the Study:
- To rigorously constrain mantle viscosity parameters using global plate motion data.
- To develop a robust method for resolving tectonic features and mantle dynamics.
Main Methods:
- Combined a scalable nonlinear Stokes solver with an adjoint-based Bayesian approach.
- Utilized global plate motions as constraints, incorporating factors like plate cooling and lithospheric thickness.
- Assumed constant grain size in the upper mantle for modeling.
Main Results:
- Achieved a good fit to global plate motions with a nonlinear upper mantle stress exponent of 2.43 ± 0.25.
- Determined a low yield stress (151 ± 19 MPa) necessary for slab bending and asymmetrical subduction.
- Found variable megathrust strength across different subduction zones, with South America showing higher strength.
Conclusions:
- The study successfully models global plate motions by constraining mantle viscosity.
- Results highlight the importance of yield stress in subduction dynamics and slab pull.
- Variations in megathrust strength have significant implications for understanding megathrust earthquake stresses.
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